Pub Date : 1998-01-19DOI: 10.1109/RAMS.1998.653714
C. Cassady, L. Maillart, R. Bowden, B. Smith
The intention of the effort presented is to characterize the solution to a general class of preventive maintenance optimization problems. Successive lengths of operating periods and the successive repair times for a piece of equipment are each assumed to be i.i.d. Weibull random variables. The equipment is subjected to an age replacement preventive maintenance policy and the successive preventive maintenance times are assumed to be i.i.d. Weibull random variables. An optimal age replacement policy is a policy, T/sub age/*, that maximizes A/sub avg/(T/sub use/), the average availability of the equipment over its useful life (T/sub use/
{"title":"Characterization of optimal age-replacement policies","authors":"C. Cassady, L. Maillart, R. Bowden, B. Smith","doi":"10.1109/RAMS.1998.653714","DOIUrl":"https://doi.org/10.1109/RAMS.1998.653714","url":null,"abstract":"The intention of the effort presented is to characterize the solution to a general class of preventive maintenance optimization problems. Successive lengths of operating periods and the successive repair times for a piece of equipment are each assumed to be i.i.d. Weibull random variables. The equipment is subjected to an age replacement preventive maintenance policy and the successive preventive maintenance times are assumed to be i.i.d. Weibull random variables. An optimal age replacement policy is a policy, T/sub age/*, that maximizes A/sub avg/(T/sub use/), the average availability of the equipment over its useful life (T/sub use/</spl infin/). The relationship between T/sub age/* and the parameters of the previously mentioned Weibull distributions is approximated by a first-order polynomial function. The model is formulated through regression analysis of data obtained through simulation-optimization techniques. Model validation is presented. In general, the model predicts an optimal T/sub age/ close to the true optimal. The model, however, tends to prescribe less frequent preventive maintenance than the true optimal policy and is not useful in some in situations where the true optimal T/sub age/ is very small.","PeriodicalId":275301,"journal":{"name":"Annual Reliability and Maintainability Symposium. 1998 Proceedings. International Symposium on Product Quality and Integrity","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129497034","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1998-01-19DOI: 10.1109/RAMS.1998.653800
A. Dumai, D. Ingman
A new damage accumulation approach presents an alternative interpretation for the bi-modality of fiber optics strength distribution. This approach is applied in order to improve the prediction of the mechanical reliability of optical fibers. The presented work shows that this approach can be used as an effective tool for the assessment of fibers strength dynamics. The data, obtained by simple tensile tests, is analyzed independent of any fracture mechanics models. The obtained experimental results support the theory of dynamic damage accumulation. It also suggests an alternative way of acceptance testing, quality assurance qualification, assessment the dynamics of fatigue and aging etc.
{"title":"Prediction of tensile-strength distribution of optical fibers","authors":"A. Dumai, D. Ingman","doi":"10.1109/RAMS.1998.653800","DOIUrl":"https://doi.org/10.1109/RAMS.1998.653800","url":null,"abstract":"A new damage accumulation approach presents an alternative interpretation for the bi-modality of fiber optics strength distribution. This approach is applied in order to improve the prediction of the mechanical reliability of optical fibers. The presented work shows that this approach can be used as an effective tool for the assessment of fibers strength dynamics. The data, obtained by simple tensile tests, is analyzed independent of any fracture mechanics models. The obtained experimental results support the theory of dynamic damage accumulation. It also suggests an alternative way of acceptance testing, quality assurance qualification, assessment the dynamics of fatigue and aging etc.","PeriodicalId":275301,"journal":{"name":"Annual Reliability and Maintainability Symposium. 1998 Proceedings. International Symposium on Product Quality and Integrity","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115288624","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1998-01-19DOI: 10.1109/RAMS.1998.653810
Billy M. DeBusk
COTS (commercial off the self) equipment use in military systems is increasing. Reliability engineers must change their paradigm to meet the challenges involved with using COTS equipment in military system designs. Systems that use COTS equipment still require reliability engineering efforts. Indeed, reliability tasks are equally as important for systems that employ COTS items as they are for those that use specially designed military equipment. Even though COTS equipment designs are complete, system level reliability efforts must be performed to ensure a reliable system design, and to provide the foundations for effective logistics support. The essential reliability analysis/tasks that must be performed are reliability predictions, system level failure mode effects and criticality analysis (FMECA), failure reporting, corrective action development and reliability verification. Predictions of COTS equipment reliability are essential and often are available from the manufacturer, however some adjustments may be required. A strategy for ESS of COTS equipment is to first accept the product as delivered, monitor failure data for trends, then determine the need for additional screening. FMECAs performed on systems utilizing COTS equipment are limited to consideration of equipment power and interface signal failures. Most COTS equipment manufacturers provide failure analysis and corrective action support for trend failures. Observed MTBF data on COTS equipment is essential to accurately predicting the reliability of future generations of COTS equipment used in similar environments.
{"title":"Managing the reliability of COTS-based military systems","authors":"Billy M. DeBusk","doi":"10.1109/RAMS.1998.653810","DOIUrl":"https://doi.org/10.1109/RAMS.1998.653810","url":null,"abstract":"COTS (commercial off the self) equipment use in military systems is increasing. Reliability engineers must change their paradigm to meet the challenges involved with using COTS equipment in military system designs. Systems that use COTS equipment still require reliability engineering efforts. Indeed, reliability tasks are equally as important for systems that employ COTS items as they are for those that use specially designed military equipment. Even though COTS equipment designs are complete, system level reliability efforts must be performed to ensure a reliable system design, and to provide the foundations for effective logistics support. The essential reliability analysis/tasks that must be performed are reliability predictions, system level failure mode effects and criticality analysis (FMECA), failure reporting, corrective action development and reliability verification. Predictions of COTS equipment reliability are essential and often are available from the manufacturer, however some adjustments may be required. A strategy for ESS of COTS equipment is to first accept the product as delivered, monitor failure data for trends, then determine the need for additional screening. FMECAs performed on systems utilizing COTS equipment are limited to consideration of equipment power and interface signal failures. Most COTS equipment manufacturers provide failure analysis and corrective action support for trend failures. Observed MTBF data on COTS equipment is essential to accurately predicting the reliability of future generations of COTS equipment used in similar environments.","PeriodicalId":275301,"journal":{"name":"Annual Reliability and Maintainability Symposium. 1998 Proceedings. International Symposium on Product Quality and Integrity","volume":"214 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133892119","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1998-01-19DOI: 10.1109/RAMS.1998.653716
W. Zimmer, J. B. Keats, R. Prairie
A new model is proposed for the characterization of failure distributions which allows a monotone characterization for distributions with nonmonotone hazard or failure rates. The new model is based on the log odds rate and can be seen to characterize a failure time distribution in terms of increasing log odds rate (ILOR) and decreasing log odds rate (DLOR) in a manner similar to the IFR and DFR concepts. The model is described and developed sufficiently in this paper to allow a reliability engineer to use the characterizations based on it. Examples are provided which illustrate how one can use log odds plots to indicate whether a distribution has ILOR or DLOR in terms of failure time, log failure time or log-log failure time. It is believed that this new model will give reliability engineers more alternative choices, more intuitive choices and more organized choices in the failure time distributions when the failure rate is nonmonotone or the IFR concept appears to be too stringent.
{"title":"Characterization of nonmonotone hazards","authors":"W. Zimmer, J. B. Keats, R. Prairie","doi":"10.1109/RAMS.1998.653716","DOIUrl":"https://doi.org/10.1109/RAMS.1998.653716","url":null,"abstract":"A new model is proposed for the characterization of failure distributions which allows a monotone characterization for distributions with nonmonotone hazard or failure rates. The new model is based on the log odds rate and can be seen to characterize a failure time distribution in terms of increasing log odds rate (ILOR) and decreasing log odds rate (DLOR) in a manner similar to the IFR and DFR concepts. The model is described and developed sufficiently in this paper to allow a reliability engineer to use the characterizations based on it. Examples are provided which illustrate how one can use log odds plots to indicate whether a distribution has ILOR or DLOR in terms of failure time, log failure time or log-log failure time. It is believed that this new model will give reliability engineers more alternative choices, more intuitive choices and more organized choices in the failure time distributions when the failure rate is nonmonotone or the IFR concept appears to be too stringent.","PeriodicalId":275301,"journal":{"name":"Annual Reliability and Maintainability Symposium. 1998 Proceedings. International Symposium on Product Quality and Integrity","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130384854","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1998-01-19DOI: 10.1109/RAMS.1998.653721
H. C. Noriega, P. F. F. Frutuoso e Melo
Surveys of preventive maintenance (PM) models for stochastically deteriorating/improving nonrepairable systems have been extensively studied. As yet, this same kind of survey for nonstationary repairable systems has not been performed. This paper discusses a maintenance model for a multi-unit nonstationary repairable system with its components failure pattern modeled as nonstationary stochastic point processes under economic and availability dependency criteria. The methodology is presented and tested with a numerical example. The results obtained show the existence of optimal maintenance actions in which both costs and benefits (availability) can be quantified and where an optimum balance between both is obtained.
{"title":"A nonstationary point-process maintenance-model for multi-unit systems","authors":"H. C. Noriega, P. F. F. Frutuoso e Melo","doi":"10.1109/RAMS.1998.653721","DOIUrl":"https://doi.org/10.1109/RAMS.1998.653721","url":null,"abstract":"Surveys of preventive maintenance (PM) models for stochastically deteriorating/improving nonrepairable systems have been extensively studied. As yet, this same kind of survey for nonstationary repairable systems has not been performed. This paper discusses a maintenance model for a multi-unit nonstationary repairable system with its components failure pattern modeled as nonstationary stochastic point processes under economic and availability dependency criteria. The methodology is presented and tested with a numerical example. The results obtained show the existence of optimal maintenance actions in which both costs and benefits (availability) can be quantified and where an optimum balance between both is obtained.","PeriodicalId":275301,"journal":{"name":"Annual Reliability and Maintainability Symposium. 1998 Proceedings. International Symposium on Product Quality and Integrity","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121764057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1998-01-19DOI: 10.1109/RAMS.1998.653785
J. Bowles, J. Dobbins
High availability is driven by two types of factors: customer site factors such as the frequency of software and hardware upgrades, and system factors such as failure and repair rates, most often associated with mathematical models of reliability and availability. In this paper we describe several tools to assess the effects of these factors on the availability of high availability transaction processing (HATP) systems and make the expected level of performance more understandable to customers who purchase such systems, sales people who sell them, and managers who must make decisions based on the system availability. We employ a survey methodology to identify the key customer site factors that drive availability; we illustrate an accurate but greatly simplified technique for modeling system availability based on the internal system factors; and we apply statistical design of experiments and control chart methodologies to better understand the variability inherent in the system performance.
{"title":"High-availability transaction processing: practical experience in availability modeling and analysis","authors":"J. Bowles, J. Dobbins","doi":"10.1109/RAMS.1998.653785","DOIUrl":"https://doi.org/10.1109/RAMS.1998.653785","url":null,"abstract":"High availability is driven by two types of factors: customer site factors such as the frequency of software and hardware upgrades, and system factors such as failure and repair rates, most often associated with mathematical models of reliability and availability. In this paper we describe several tools to assess the effects of these factors on the availability of high availability transaction processing (HATP) systems and make the expected level of performance more understandable to customers who purchase such systems, sales people who sell them, and managers who must make decisions based on the system availability. We employ a survey methodology to identify the key customer site factors that drive availability; we illustrate an accurate but greatly simplified technique for modeling system availability based on the internal system factors; and we apply statistical design of experiments and control chart methodologies to better understand the variability inherent in the system performance.","PeriodicalId":275301,"journal":{"name":"Annual Reliability and Maintainability Symposium. 1998 Proceedings. International Symposium on Product Quality and Integrity","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128036350","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1998-01-19DOI: 10.1109/RAMS.1998.653777
J. English, A. Mendoza
Reliability modeling of time-dependent systems has been the subject of many research development efforts. Even within the context of simple series or parallel systems, the determination of the mean time to failure at the system level can be complex and can exceed the available resources for analytical development and computation. The approach presented is suitable for application in the engineering design of systems for which the failure times of the individual components can be reasonably assumed to be normally distributed. Further research extensions include a more comprehensive analysis of the approach. In particular, the authors conduct a robustness analysis of the approach when departures from the normality assumption are encountered and apply the approach to complex networks.
{"title":"A discretizing approach for time-dependent reliability modeling","authors":"J. English, A. Mendoza","doi":"10.1109/RAMS.1998.653777","DOIUrl":"https://doi.org/10.1109/RAMS.1998.653777","url":null,"abstract":"Reliability modeling of time-dependent systems has been the subject of many research development efforts. Even within the context of simple series or parallel systems, the determination of the mean time to failure at the system level can be complex and can exceed the available resources for analytical development and computation. The approach presented is suitable for application in the engineering design of systems for which the failure times of the individual components can be reasonably assumed to be normally distributed. Further research extensions include a more comprehensive analysis of the approach. In particular, the authors conduct a robustness analysis of the approach when departures from the normality assumption are encountered and apply the approach to complex networks.","PeriodicalId":275301,"journal":{"name":"Annual Reliability and Maintainability Symposium. 1998 Proceedings. International Symposium on Product Quality and Integrity","volume":"126 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133991521","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1998-01-19DOI: 10.1109/RAMS.1998.653811
K. Hjelmgren, S. Svensson, O. Hannius
This paper presents a reliability analysis of two options to a fault-tolerant full authority digital electronic control system (FADEC) intended for control of an aircraft gas turbine engine. The study concentrates on an application for an aircraft equipped with a single engine, thus placing very hard constraints on the reliability of the FADEC. The analysis is based on Markov modeling and a method of mapping state probabilities. Using this method, the influence of varying criticality among the flight mission phases can be investigated, as can the influence of not using the common assumption of "perfect from start". The study shows that latent faults together with incomplete repair between flights (i.e. the system is not perfect from start) have a clear influence on the assessed reliability. How important these faults are depends to a great extent on the probability of repair. The study also indicates that phase modeling is of less importance, mainly because the phases are quite similar in the specific model and the assumed flight mission time is fairly short compared to MTTF for the components of the FADEC.
{"title":"Reliability analysis of a single-engine aircraft FADEC","authors":"K. Hjelmgren, S. Svensson, O. Hannius","doi":"10.1109/RAMS.1998.653811","DOIUrl":"https://doi.org/10.1109/RAMS.1998.653811","url":null,"abstract":"This paper presents a reliability analysis of two options to a fault-tolerant full authority digital electronic control system (FADEC) intended for control of an aircraft gas turbine engine. The study concentrates on an application for an aircraft equipped with a single engine, thus placing very hard constraints on the reliability of the FADEC. The analysis is based on Markov modeling and a method of mapping state probabilities. Using this method, the influence of varying criticality among the flight mission phases can be investigated, as can the influence of not using the common assumption of \"perfect from start\". The study shows that latent faults together with incomplete repair between flights (i.e. the system is not perfect from start) have a clear influence on the assessed reliability. How important these faults are depends to a great extent on the probability of repair. The study also indicates that phase modeling is of less importance, mainly because the phases are quite similar in the specific model and the assumed flight mission time is fairly short compared to MTTF for the components of the FADEC.","PeriodicalId":275301,"journal":{"name":"Annual Reliability and Maintainability Symposium. 1998 Proceedings. International Symposium on Product Quality and Integrity","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116547425","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1998-01-19DOI: 10.1109/RAMS.1998.653805
W. Ching
This paper studies optimal (s,S) policies for production planning in manufacturing systems of unreliable machines in tandem. The manufacturing system produces one type of product. This type of manufacturing system occurs in many applications. In our study we assume that the inter-arrival time of a demand and processing time for one product in each machine are exponentially distributed. Each machine is unreliable and is subject to a sequence of repairing processes when it is broken down. The up time and the repairing time in each phase are assumed to be exponentially distributed. We study the manufacturing system by considering each machine as an individual system with random supply and demand. The Markov Modulated Poisson Process (MMPP) is used to model the random process of supply. For each machine, we obtain the approximated optimal (s,S) policies which minimizes the average running cost of its buffer.
{"title":"Optimal (s,S) policies for manufacturing systems of unreliable machines in tandem","authors":"W. Ching","doi":"10.1109/RAMS.1998.653805","DOIUrl":"https://doi.org/10.1109/RAMS.1998.653805","url":null,"abstract":"This paper studies optimal (s,S) policies for production planning in manufacturing systems of unreliable machines in tandem. The manufacturing system produces one type of product. This type of manufacturing system occurs in many applications. In our study we assume that the inter-arrival time of a demand and processing time for one product in each machine are exponentially distributed. Each machine is unreliable and is subject to a sequence of repairing processes when it is broken down. The up time and the repairing time in each phase are assumed to be exponentially distributed. We study the manufacturing system by considering each machine as an individual system with random supply and demand. The Markov Modulated Poisson Process (MMPP) is used to model the random process of supply. For each machine, we obtain the approximated optimal (s,S) policies which minimizes the average running cost of its buffer.","PeriodicalId":275301,"journal":{"name":"Annual Reliability and Maintainability Symposium. 1998 Proceedings. International Symposium on Product Quality and Integrity","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133417968","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1998-01-19DOI: 10.1109/RAMS.1998.653545
M. H. McIntyre
Integrated product development (IPD) is a systematic approach to product (or service) development that achieves a timely collaboration of necessary disciplines throughout the product life cycle to better satisfy customer needs. This paper provides an architecture and content description for IPD. The final product due in the first quarter of 1998 describes a formal model based on industry input for IPD and the roles of teams within it. The intent of the paper is to present the current architecture and collect feedback on practitioner-targeted, short, informational presentations and what else practitioners who help develop and implement processes need/want to know to want to try out the IPD model.
{"title":"An integrated product development framework","authors":"M. H. McIntyre","doi":"10.1109/RAMS.1998.653545","DOIUrl":"https://doi.org/10.1109/RAMS.1998.653545","url":null,"abstract":"Integrated product development (IPD) is a systematic approach to product (or service) development that achieves a timely collaboration of necessary disciplines throughout the product life cycle to better satisfy customer needs. This paper provides an architecture and content description for IPD. The final product due in the first quarter of 1998 describes a formal model based on industry input for IPD and the roles of teams within it. The intent of the paper is to present the current architecture and collect feedback on practitioner-targeted, short, informational presentations and what else practitioners who help develop and implement processes need/want to know to want to try out the IPD model.","PeriodicalId":275301,"journal":{"name":"Annual Reliability and Maintainability Symposium. 1998 Proceedings. International Symposium on Product Quality and Integrity","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129165667","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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